Electric heating appliance



Feb. 2, 1954 E. SPURR ELECTRIC HEATING APPLIANCE 2 Sheecs-Shee+u 1 FiledJune lO, 1952 E. SPURR ELECTRIC HEATING APPLIANCE.'

Feb. 2, 1954 2 Sheets-Sheet 2 Filed June lO, 1952 Patenterl Feb. 2, 19542,668,220 ELEcrRIc HEATING APPLIANCE Edward Spurr, Orange Grove,Johannesburg. Transvaal, Union of South Africa Application June 10,1952, Serial No. 292,619

Claims priority, application Union of South Africa June 12, 1951 3Claims. (Cl. 219-34) This invention relates to electric heatingappliances of the kind comprising an electric resistor elementassociated with a polished reflector surface for directing heat from theappliance as a beam. It provides a form or forms of such appliancehaving improvements in the construction and arrangement of the resistorelement and the reflector, and in the relative disposition of theseparts, making for cheapness of construction, reduction of repair costs,enhanced protection of the resistor and reflector parts and greatersafety in use.

According to the invention in a heating appliance of the foregoing kinda resistor element is made up of a number of separate relatively shortresistance wires electrically connected in a series arrangement byconnecting members devised to hold the several wires under tension inthe mutual disposition desired.

Such members may be arranged to present the wires which they connect, infront of a suitable reector, in a zig-zag or like tortuous path betweenelectric supply terminals to which the extreme wires are respectivelyconnected; the said connecting members occurring at and constituting theturning corners or bends in the path aforesaid.

The resistor may be presented in this way as a flat skeleton panel, i.e. with the wires and turning corner connections conforming to a planearranged in front of and parallel to the general plane of a reiiector ofapproximately equal extent with that of the said panel, the combinationbeing arranged for use vertically or at a backward inclination in theusual way of wall-fixing or pedestal radiators.

Alternatively the said connecting members may be arranged so as topresent the Wires constituting the resistor element in a curvedarrangement, e. g. with the Wires conforming substantially to thesurface or envelope of a `ligure of revolution, e. g. the surface of animaginary cylinder or prism or other such solid figure, the componentwires extending generally from connecting member to connecting memberand end 'terminals in alternately opposite senses substantially coplanarwith the axis of generation of the said surface or envelope. Thereiiector in such a case is arranged to the concave side of theaforementioned surface or envelope, itself conforming to a surface orenvelope of a figure of revolution, cylinder, prism or other solidfigure, similar to the said surface but of smaller radius or modiiiedform providing suitable clearance between the resistor wires and theactive surface of the reflector.

According to the invention also, in a heating appliance wherein theresistor comprises straight lengths of resistance wire, which may be theaforementioned separate wires series-connected electrically byconnecting and tensioning members and following a path in which theseveral Wires are substantially parallel the reilector may be formedwith corrugations or the like in and along the several valleys of whichthe several wires of the resistor element may extend so that the wiresare individually provided with concave more or less semi-cylindricalreflectors, the combined effects of which provisions being to projectthe rearwardly radiating fractions of the heat rays from the componentwires of the resistor element in a parallel or substantially parallelbeam through the plane or the like occupied by the resistor element.More particularly the corrugation form is made substantially cylindricalin the valleys aforesaid, and the wires are arranged each to occupy aline parallel to the cylinder axis at approximately half the radius ofthe corrugations from their axes. This preferred relative disposition ofthe wires and their respective reflector surfaces practically obviatesloverheating of the wires by back rays from the reflector, which areinstead projected in parallelism past the wires.

The invention extends to detail constructional features in themanufacture of electric heaters in which the main features above setforth are embodied preferably in combination, as now to be described byway of example, with reference to the accompanying drawings wherein:

Figure 1 is a sectional elevation of a pedestaltype heater constructedaccording to the invention;

Figure 2 is a fragmentary sectional plan on the line II-II of Figure 1;

Figure 3 is a front elevation of the heater, broken in width (toindicate that it may be of any desired width) and partly in section onthe line III- III of Figure l;

Figure 4 is a fragmentary front elevation showing` a corner of theheater and in l.broken lines certain internal parts and fittings.

The illustrated heater comprises a body I of square or oblong frontalform, open at 2 over its rear and providing a framed front opening 3through which the interior is visible, the frame cross-section being ofapproximately J-form as shown in Figures 1 and 2, the foot 4 of whichform coincides with or frames the front opening, the leg 5 constitutingthe periphery of the body. The body may be a casting, or a pressing fromsuitable `metal, a moulding of adequately refractory material, or builtup from sheet material in any way.

Two rigid beams 6 and 1 of non-conducting, refractory material are xedacross the inside of the body parallel to and one above the other withthe upper beam linear the rear of the body; and from these the resistorelement 8 is supported in a plane parallel to the front of the body nearthe medial plane thereof.

The resistor element is built up from a number of like separate lengths8a, 3b, 8c etc., of suitable resistance wire starting from an end one 9aof a series of highly flexible, e. g. springy brass, contacts orconnector brackets 9a., 9b, 9c etc., of the plan forms shown partly inbroken lines in Figure 2, fixed in equispaced arrange-,- ment, e. g.about 1" apart along the underside of the lower beam l so as to projectforwardly therefrom. From the said end bracket 9a the first length ofwire la runs straight upward to connect, under tension, with thecorresponding end bracket les of a second series of contact or connectorbrackets lea, 10b, iec etc., arranged along the upper side of the upperbeam 6 in similar and if desired staggered relationship with the lowerseries of brackets. The second wire (8b in Figure 3) extends downwardlyunder tension from the said upper end bracket ma to the second bracket9b of the lower series; the third wire Bc from the latter bracket to thesecond of the upper brackets; the fourth wire from this last bracket tothe third lower bracket, and so on over the width of the interior of thebody and toy such an extent that the resistor panel or skeleton thusbuilt up fills an area about equal to and inwardly opposite to thefrontal opening 3 of the body I.

More particularly, the lower brackets may be strips of spring brass orthe like bent up from blank into a modified Z-form or Sfforrn, as bestseen in Figures l and 3, for fixing conveniently by the head part 9 tothe underside of the lower beam, its leg extending downwardly and itsfoot projecting forwardly from the beam and being rolled upwardly andinwardly into a hairpin bend the tail e f which lies below and a shortdistance in front of the lower beam.

The tail part or parts of each such bracket accommodates a very liberalspringing action in the vertical direction and provides the lowerconnection for either one or two adjacent wires to be held as above inthe plane of the resistor panel or skeleton. For this purpose each tailis bifurcatedv and the thus separated tail portions are `each curledround as at 9" and provided with a slot, notch, or the like into whichthe lower end of a wire may be readily inserted to engage in an upwarddirection a head, bead, nipple or the like le provided at the wire endto form a readily made and unmade connection of the wire to the bracketand an electrically conductive connection between the wire or each ofthe two wires which may thus be fixed to each bracket.

The upper brackets, made in a somewhat similar fashion, are of a lessdistorted Z-formwith their feet' as le fixed to the top of the upperbeam 6, their legs extending-'upwardly and their heads 'as IQ projectingstraight forwardly beyond the front of the uper beam to finish in'bifurcated, notched, or like tails as it by which upper ends of thewires. may be fixed and connected singly or in pairs in a similar way tothat described with reference to the lower brackets.

The upper brackets being located above the wires are-subjected to higherWorking tempera- Cil tures than are the lower brackets and are ofsubstantially rigid construction as they are not expected in suchconditions to provide the wiretensioning spring effect, foraccommodating expension and contraction of the resistor wires andmaintaining them in taut condition at all times; the said effect beingprovided by the much more springy lower brackets which operate in thecooler conditions below the wires.

Binding posts or terminals as Il and I2 are conveniently embodied aspart of the fixings for the end brackets on the lower beam so that theresistor element is series-wired through the several component wires.

The reflector I3 consists of a sheet of polished metal plate of anoutline corresponding to the extent of the resistor panel or skeletonwith a safe marginal clearance distance from the upper and lowerbrackets, and is mounted in any convenient manner inside the heater bodyclose to but so as to leave an air gap between it and the fronts of thebeams aforesaid, e. g. fixed as shown, using spacers as i4. Thereflector sheet is corrugated vertically with the several frontcorrugation valleys 13a rearwardly coincident with the several wiresaforesaid. The form of the corrugations and their disposition inrelation to these wires are as already indicated herein; so that theheat is projected very largely as a beam of parallel rays and forwardlythrough the front opening of the heater body.

The body of the heater is provided with louvres as i5 and i5 through itsupper and lower walls or peripheral parts to admit of convection aircurrents taking place upwardly through the heater. Such louvres may bein the form o f series of parallel slots and these are preferablyprovided with external guards as I 5 and IB', against access, in theform of ribs or fins alternating with the slots and incidentallyproviding extended heat transfer surfaces of the heater body.

For the rest, in this particular construction of heater, a plate orother refractory glass panel il is applied over the front opening fromthe inside to t, with a suitable cushioning marginal seal I3, againstthe inner extremity 4 of the J- section of the body; and an L.-sectionmetal shrouding frame i9 of outline corresponding generally to the shapeof the front opening is applied inside the glass to extend therefrominwardly to a plane close to the front of the resistor and reectorcombination. The interior surface 49a of the shroud may, if desired, becurved, e. g. to a parabolic or like concave or iiared section.

Preferably the beams, shroud and intervening resistor and reector aredesigned for sandwiching together in correct relative positions beforeassembly or during assembly in the heater body after the front glass hasbeen inserted, and for fixing in iinal position by a number of bolts,studs or the like as 2B and 2i entering suitable bosses, webs, lands orthe like as 23 and 2li provided inside the front of the body and/o1' bythe shroud flange. Any suitable form of back plate 25 may be applied asa closure over the rear of the heater body for protection of itscontained parts.

Adverting to the wires used for the resistor element, these arepreferably of relatively stout or heavy gauge, suited to operation atrelatively low temperature besides being more suitable for use in themanner above explained whereby they may be individually and easilyreplaced when burnt out vor damaged.

The heater particularly described above may be provided with a base orwith feet as 26 for pedestal or like mounting, e. g. with the bodytilted backwardly as shown; or it may be pro vided with means enablingit to be set into or against a wall or the like.

In a modification the front glass may be replaced by a copper or othersuitable metal front panel, with the whole supported on its back orotherwise to provide a domestic hot plate, toaster or other suchappliance.

In a further modication the heater may be designed to present itsresistor element and associated reflector in a curved form, or even incylindrical or like column or pillar form, whereof a verticalhalf-section taken in any radial plane may closely resemble the verticallongitudinal section of the construction particularly described above.

I claim:

l. In a radiant-convector type heating device, comprising a rectangularframe having slotted upper and lower horizontal members, spacedhorizontal bars of electrically conductive and refractory material whichare rigidly mounted across the upper and lower regions of the frame, acorrugated reilector xed to said bars and spanning the space betweensaid bars with the corrugations substantially vertically disposed, aseparate length of resistor wire located in each forwardly directedcorrugation valley of the reector in constant spaced relationship to thesubstantial semi-circular surfaces of the respective corrugationvalleys, a transparent refractory panel mounted across the front openingof the rectangular frame in parallel spaced relationship to the face ofthe corrugated reiiector to permit heat radiation therethrough and forforming a convection cavity, a plurality of spaced rigid bracketsmounted cantilever fashion on the upper bar for attachment of the upperends of the separate resistor wires, a plurality of spaced resilientfixing brackets'mounted cantilever fashion to the lower bar in thecoolest zone of the heating device for connection of the bottom ends ofsaid wires and taut retention of the wires in the aforesaid constantspaced relationship relative to the reflector corrugation valleys duringexpansion and contraction of said wires, the arrangement being such thatthe alternate pairs of rigid wire brackets are electrically connected,while the resilient mounting brackets are similarly connected for allthe resistor wires to be connected in series.

2. A radiant-convector type heating device, as claimed in claim l,wherein said resilient mounting bracket provides prong-like extensionsprojecting cantilever-fashion forwardly of the reiector bottom edge andbent from blank into a modified S-like shape having the upper regionsecured to the said lower bar, whereas the bottom end is bent back uponitself in spaced relationship for the resistor wire connecting end to bedisposed above the intermediate region of the bottom loop and providesmovement of said end along compensating opposingly centred arcsproviding straightlined deflection of said ixing end and resultantconstant spacing of the resistor wire relative to the respectivereflector corrugation valleys.

3. In a radiant-convector type heating device as claimed in claim 1,wherein each resistor wire is located in spaced relationship to theconcave face of the relative reflector corrugation valley atapproximately half the distance of such concave face to the focus orcentering line of the concave face to obviate overheating of the wire byback rays from the reflector.

EDWARD SPURR.

Referenees Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,007,125 Madsen Oct. 31, 1911 1,014,161 Madsen Jan. 9, 19121,023,475 Madsen Apr. 16, 1912 1,317,883 Meacham Oct. 7, 1919 1,644,911Braun Oct. 11, 1927 1,652,686 Schoenfeld Dec. 13, 1927 2,379,820 MendezJuly 3, 1945 2,613,308 Mirand Oct. 7, 1952 FOREIGN PATENTS NumberCountry Date 445,853 Great Britain Apr. 20, 1936

